The present invention relates to a local area communication network.
A great deal of discussion can be seen in the recent literature regarding local networks and their applicability to many of today's local area communication needs. These needs have primarily consisted of data communication applications such as computer-to-computer data traffic, terminal-to-terminal data traffic, and the like. More recently, a new line of thought has been apparent. It is the desire to integrate voice communication on local data networks. The reason for this is threefold: (i) voice is an office communication application just as computer data, facsimile, etc.; (ii) recent advances in vocoder technology have shown that digitized speech constitutes a digital communication application which is within the capabilities of local area data networks; and (iii) today's local network architectures, especially the broadcast bus type, offer very elegant solutions to the local communications problems, from both the point of view of flexibility in satisfying growth and variability in the environment.
While existing solutions are elegant, they are not without their limitations in performance. Some of these limitations arise as the characteristics of the environment and data traffic requirements being supported by these solutions deviate from those assumed in the original design. Examples of such characteristics are: Packet length distribution, packet generation pattern, channel data rate, delay requirements and geographical area to be spanned.
One prior art approach is a bidirectional broadcast system (BBS) architecture based on a carrier sense multiple access (CSMA) mechanism as exemplified by the so-called ETHERNET. Another prior art approach is a unidirectional broadcast system (UBS) architecture with a round-robin access scheme.
A problem with a CSMA bidirectional broadcast system is that it can be shown that the effort required to achieve higher channel bandwidths with the hope of achieving a network throughput proportional to the channel speed is unfortunately rewarded only by a marginal improvement.
The limitation with unidirectional broadcast systems operating with the existing round-robin scheme is that the maximum throughput for such a system exhibits similar performances as for a CSMA bidirectional broadcast system, and as such both approaches suffer of an overhead per packet transmission.
There is a need therefore for an improved local area communication network which overcomes the problems of prior art systems. In view of the above background, it is an objective of the present invention to provide an improved local area communication network.